Virtually all commercial and most companion animals are affected by ectoparasites, often resulting in clinical disease and subclinical conditions that adversely affect the animal. Insects such as Phthiraptera (lice) and Diptera (flies), are among the most economically important ectoparasites affecting animal production. Insects such as Siphonaptera (fleas) are pests to companion animals. Ticks and mites in the order Acarina are serious pests of both production and companion animals. Ectoparasitic infection and infestation seriously affect the economies of raising production animals and also are a source of great concern for companion animals. New economic methods and compositions for the prevention, treatment and control of ectoparasites in warm-blooded animals are constantly being sought.